Particulate Filter Regeneration Control System and Method

ABSTRACT

Systems and methods for controlling regeneration of a diesel particulate filter in a vehicle engine exhaust include detecting a distance of an object from the exhaust and controlling a regeneration event if the distance is less than a threshold value. The system and method may include a particulate filter disposed in the exhaust of the vehicle and a proximity sensor disposed adjacent an exhaust opening and positioned to detect presence of an object near the opening. A controller in communication with the proximity sensor is adapted for controlling regeneration of the particulate filter in response to the proximity sensor detecting the object near the opening.

TECHNICAL FIELD

The present disclosure relates to particulate filter regeneration.

BACKGROUND

A byproduct of fuel combustion, especially diesel fuel combustion, is carbon particles, which are referred to as soot. Emissions regulations limit the amount of soot and particulates that an engine may exhaust to the environment.

Emission control devices, such as particulate filters, reduce the amount of soot emissions from an engine by trapping soot particles. As the particulate filter becomes saturated with soot, the filter may be regenerated, to decrease the amount of trapped particulate matter and restore the performance of the filter. Regeneration is typically achieved by raising the temperature of the filter to a predetermined level to oxidize or burn the accumulated particulate matter.

Regeneration may be accomplished by injecting additional fuel into the exhaust stream, or altering the operation of the engine to increase exhaust temperature. Typically, filter regeneration may be performed during normal driving conditions and does not affect vehicle driveability so that the driver is unaware that regeneration of the filter has occurred. However, various applications may also include an operator commanded regeneration, such as during vehicle servicing, or for off-road vehicles including industrial and construction vehicles, for example.

SUMMARY

A system and method for controlling regeneration of a diesel particulate filter in a vehicle engine exhaust is provided. In one embodiment, the system and method include detecting a distance of an object from the exhaust and controlling a regeneration event if the distance is less than a threshold value. In another embodiment, the system and method include a particulate filter disposed in the exhaust of the vehicle and a proximity sensor disposed adjacent an exhaust opening and positioned to detect presence of an object near the opening. A controller in communication with the proximity sensor is adapted for controlling regeneration of the particulate filter in response to the proximity sensor detecting the object near the opening.

According to another embodiment, the system and method include terminating the regeneration event if the distance detected by the proximity sensor is less than the threshold value. In a further embodiment, the system and method include preventing initiation of the regeneration event if the distance detected by the proximity sensor is less than the threshold value. In yet another embodiment, the system and method include displaying a message for an operator if the distance is less than the threshold value.

Embodiments according to the present disclosure may provide various advantages. For example, systems and methods for controlling DPF regeneration according to the present disclosure reduce or eliminate the possibility for heat discharged during regeneration to adversely affect any object or person near the vehicle exhaust. Use of existing vehicle proximity sensors that may also be used for parking and/or back-up maneuvers provides additional feature functionality without requiring additional vehicle hardware and associated costs and complexity.

The above advantages and other advantages and features will be readily apparent from the following detailed description of representative embodiments when taken in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram illustrating operation of a system or method for controlling an internal combustion engine and exhaust system according to an embodiment of the present disclosure;

FIG. 2 illustrates a vehicle including the engine and exhaust system according to FIG. 1; and

FIG. 3 is a flow chart illustrating operation of a system or method for controlling regeneration of a particulate filter according to an embodiment of the present disclosure.

DETAILED DESCRIPTION

Detailed representative embodiments are disclosed herein; however, it is to be understood that the disclosed embodiments are merely examples that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the claimed features. As those of ordinary skill in the art will understand, various features of the present disclosure as illustrated and described with reference to any one of the Figures may be combined with features illustrated in one or more other Figures to produce embodiments of the present disclosure that may not be explicitly illustrated or described. The combinations of features illustrated provide representative embodiments for typical applications. However, various combinations and modifications of the features consistent with the teachings of the present disclosure may be desired for particular applications or implementations.

FIG. 1 illustrates a schematic diagram showing one cylinder of multi-cylinder engine 10, which may be included in a propulsion system of a vehicle, such as an automobile, truck, or stationary or mobile construction or industrial vehicle, for example. Those of ordinary skill in the art will recognize that various components of engine 10 may vary depending on the particular type of engine and/or the particular application. Engine 10 generally represents a compression ignition engine powered by diesel fuel. However, various features of the present disclosure may also be applied to spark-ignited engines powered by gasoline, gaseous fuel, or dual fuel engines, for example.

Engine 10 may be controlled at least partially by a control system including a controller 12 and by input from a vehicle operator 14 via an input device 16. In this example, the input device 16 includes an accelerator pedal and a pedal position sensor 18 for generating a proportional pedal position signal PP. Other input devices may also be used. For example, in construction or industrial applications, input device 16 may be implemented by a dial, knob, lever, digital control, etc. The combustion chamber or cylinder 30 of engine 10 may include combustion chamber walls 32 with a piston 36 positioned therein. The piston 36 may be coupled to crankshaft 40 so that reciprocating motion of the piston 36 is translated into rotational motion of the crankshaft 40. The crankshaft 40 may be coupled to at least one drive wheel of a vehicle via an intermediate transmission system. Further, a starter motor may be coupled to crankshaft 40 via a flywheel to enable a starting operation of engine 10.

The cylinder 30 may receive intake air via an intake passage 42 in intake manifold 44 and may exhaust combustion gases via exhaust passage 48. The intake manifold 44 and exhaust passage 48 can selectively communicate with the cylinder 30 via respective intake valve 46 and exhaust valve 50. In some embodiments, the cylinder 30 may include two or more intake valves and/or two or more exhaust valves. A fuel injector 52 is illustrated coupled directly to the cylinder 30 for injecting fuel directly into the cylinder 30. The fuel injector 52 injects fuel in proportion to the pulse width of signal FPW received from controller 12. In this manner, the fuel injector 52 provides what is known as direct injection of fuel into the cylinder 30. The fuel injector 52 may be mounted along the side of the cylinder 30 or in the top of the cylinder, for example.

Fuel may be delivered to fuel injector 52 by a fuel system (not shown) including a fuel tank, a fuel pump, and a fuel rail. In some embodiments, the fuel injector 52 is arranged in intake passage 42 in a configuration that provides what is known as port fuel injection of fuel into the intake port upstream of the cylinder 30. Although FIG. 1 shows only one cylinder of a multi-cylinder engine, each cylinder may similarly include its own set of intake/exhaust valves, fuel injector, spark plug, etc.

The intake passage 42 may include a throttle 62 having a throttle plate 64. In this particular example, the position of the throttle plate 64 may be varied by controller 12 via a signal provided to an electric motor or actuator included with the throttle 62, a configuration that is commonly referred to as electronic throttle control (ETC). In this manner, the throttle 62 may be operated to vary the intake air provided to the cylinder 30 among other engine cylinders. The position of throttle plate 64 may be provided to the controller 12 by the throttle position signal TP. The intake passage 42 may include a mass air flow (MAF) sensor 60 and a manifold air pressure (MAP) sensor 66 for providing the MAF and MAP signals, respectively, to the controller 12. Various implementations may use other airflow control devices in combination with or in place of throttle 62. For example, applications having electromagnetically actuated intake/exhaust valves 46,50 may use valve timing to control intake airflow. Some compression ignition engines, particularly those that do not use exhaust gas recirculation, may not include a throttle 62.

The controller 12 may receive various signals from sensors coupled to engine 10. In addition to those signals previously discussed, the controller may receive signals measuring engine coolant temperature (ECT) from temperature sensor 54 coupled to cooling sleeve 56; a profile ignition pickup signal (PIP) from Hall effect sensor 58, or other suitable sensor, coupled to crankshaft 40; or throttle position (TP) from a throttle position sensor. An engine speed signal, RPM, may be generated by the controller 12 from signal PIP. The manifold pressure signal MAP from the manifold pressure sensor 66 may be used to provide an indication of vacuum, or pressure, in the intake manifold. Note that various combinations of the above sensors may be used, such as a MAF sensor 60 without a MAP sensor 66, or vice versa. During stoichiometric operation, the MAP sensor 66 can give an indication of engine torque. Further, the MAP sensor 66, along with the detected engine speed, can provide an estimate of charge, including air, inducted into the cylinder 30. In one example, sensor 58, which is also used as an engine speed sensor, may produce a predetermined number of equally spaced pulses every revolution of the crankshaft 40.

The cylinder 30, or one or more other the cylinders of engine 10, may be operated in a compression ignition mode, with or without an ignition spark provided by an associated spark plug (not shown). Further, engine 10 may be turbocharged by a compressor 70 disposed along the intake manifold 44 and a turbine 72 disposed along the exhaust passage 48 upstream of the exhaust after-treatment system 80.

An exhaust gas sensor 74 is illustrated coupled to exhaust passage 48 upstream of the exhaust gas after-treatment system 80. The exhaust gas sensor 74 may be any suitable sensor for providing an indication of exhaust gas air/fuel ratio such as a linear oxygen sensor or UEGO (universal or wide-range exhaust gas oxygen), a two-state oxygen sensor or EGO, a HEGO (heated EGO), a NOx, HC, or CO sensor. An exhaust gas recirculation (EGR) system 76 may be coupled to the exhaust passage 48. The EGR system may include an EGR valve 77 and an EGR cooler 78 disposed along the EGR conduit 79.

The exhaust gas after-treatment system 80 may include a plurality of emission control devices, each of which may carry out an exothermic reaction with excess oxygen present in the exhaust during selected conditions, such as selected temperatures. For example, the exhaust gas after-treatment system 80 may include a diesel oxidation catalyst (DOC) 82 disposed along exhaust gas conduit 48 downstream of turbine 72. A selective catalytic reduction (SCR) catalyst 84 may be disposed along the exhaust gas conduit 48 downstream of the DOC 82. The selective catalyst reduction process may use a diesel exhaust fluid injector 85. The diesel exhaust fluid injector 85 may be a urea sprayer, or any suitable ammonia source. The diesel exhaust fluid injector 85 may be disposed upstream of the SCR catalyst 84 and downstream of the DOC 82.

The exhaust gas after-treatment system 80 also includes a diesel particulate filter (DPF) 86. The DPF 86 may be disposed along the exhaust conduit 48 downstream of the SCR catalyst 84. Pressure and/or temperature sensors 88, 90, 92, and 94 may be disposed at points along the exhaust gas conduit 48 both upstream and downstream of each after-treatment device in the after-treatment system 80. Further, an oxygen sensor 96, such as an UEGO sensor, may be disposed downstream of the exhaust after-treatment system 80. It is also contemplated that in a gasoline application, the exhaust gas after-treatment system may include a particulate filter, such as a gas particulate filter (GPF).

The DPF 86 may be manufactured from a variety of materials including cordierite, silicon carbide, and other high temperature oxide ceramics. Once soot accumulation in the DPF 86 has reached a predetermined level, regeneration of the DPF 86 may be automatically initiated and controlled according to the present disclosure. Alternatively, a DPF regeneration may be requested by an associated operator alert, message, light, etc. to suggest a manual or operator-initiated DPF regeneration, which is initiated by the operator. Similarly, a DPF regeneration may be manually initiated during vehicle servicing. Soot accumulation in the DPF 86 may be identified by a pressure drop, for example across pressure and/or temperature sensors 88, 90, 92, and 94.

It should be understood that exhaust after-treatment system 80 may include a plurality of after-treatment device configurations not shown in FIG. 1. In one example, the exhaust after-treatment system 80 may only include a DOC 82. In another example, the exhaust after-treatment system 80 may include a DOC 82 followed downstream by a DPF 86. In another example, the exhaust after-treatment system 80 may include the DOC 82 followed downstream by a DPF 86 then the SCR catalyst 84. In still another example, the SCR catalyst 84 shown in FIG. 1 may be replaced with a lean NOx trap (LNT). Further, the order of the different catalysts and filters in the exhaust after-treatment system 80 may also vary. The number of pressure and/or temperature sensors disposed within the exhaust after-treatment system 80 may also vary according to the application. Though the oxygen sensor 96 is shown in FIG. 1 at a point located downstream of exhaust after-treatment devices, it may be located upstream of any of the devices in the after-treatment system 80, in which case it can only monitor the catalysts upstream of the oxygen sensor 96. It is also contemplated that in a gasoline application, the exhaust gas after-treatment system may include a three-way catalyst (TWC), or other suitable catalyst, instead of or the DOC and a GPF instead of a DPF.

Regeneration of the DPF 86 may be accomplished by heating the DPF 86 to a temperature that will burn soot particles at a faster rate than the deposition of new soot particles, for example 400-600 degrees Celsius. In one example, the DPF 86 can be a catalyzed particulate filter containing a washcoat of precious metal, such as platinum, to lower soot combustion temperature and also to oxidize hydrocarbons and carbon monoxide to carbon dioxide and water.

In another embodiment, an injector 87 may be used to deliver fuel from the fuel tank or from a storage vessel to the exhaust system to generate heat for heating the DPF 86 for regeneration purposes. The injector 87 may be located upstream of the DOC 82. In addition, late fuel injection by the injector 52 during an exhaust stroke of the piston 36 may be used to raise exhaust temperature for regeneration purposes.

Alternatively, to regenerate the DPF 86, a regeneration injection strategy may be implemented. The regeneration injection strategy may implement an injection profile including a plurality of injection events such as a pilot fuel injection, a main fuel injection, a near post fuel injection, and/or a far post fuel injection. It will be appreciated that the aforementioned fuel injections may include a plurality of injection events, in other embodiments. Thus, the DPF 86 may be regenerated during operation of the engine 10. For example, the temperature downstream of the DOC 82 and upstream of the DPF 86 may be controlled to a desired value to promote combustion of particulate matter within the DPF 86, by adjustment of the amount of the various injections. In this example, a temperature set-point downstream of the DOC 82 and upstream of the DPF 86 may be established to facilitate regeneration of the DPF 86.

The controller 12 in FIG. 1 may be a microcomputer also referred to as a central processing unit (CPU), including microprocessor unit, input/output ports, and electronic storage medium for executable programs and calibration values. Computer readable storage media may include volatile and nonvolatile storage in read-only memory (ROM), random-access memory (RAM), and keep-alive memory (KAM), for example. KAM may be used to store various operating variables or control system parameter values while the CPU is powered down. Computer-readable storage media may be implemented using any of a number of known memory devices such as PROMs (programmable read-only memory), EPROMs (electrically PROM), EEPROMs (electrically erasable PROM), flash memory, or any other electric, magnetic, optical, or combination memory devices capable of storing data, some of which represent executable instructions or code, used by the controller 12 in controlling the engine or vehicle into which the engine is mounted and for performing on-board diagnostic (OBD) monitoring of various engine/vehicle features. Computer-readable storage media may also include floppy disks, CD-ROMs, hard disks, and the like.

The controller 12 may communicate with various engine/vehicle sensors and actuators via an input/output (I/O) interface that may be implemented as a single integrated interface providing various raw data or signal conditioning, processing, and/or conversion, short-circuit protection, and the like. Alternatively, one or more dedicated hardware or firmware chips may be used to condition and process particular signals before being supplied to the controller 12.

The controller 12 may also communicate with a vehicle cluster display 98. The cluster display 98 may be located in the passenger compartment 102 to alert the driver of service information relative to engine 10 or exhaust after-treatment system 80, for example. As described in greater detail herein in FIG. 3, the controller 12 may monitor at least one exhaust after-treatment system 80 parameter to determine whether DPF regeneration is needed. Controller may display information to an operator relative to regeneration of the DPF using cluster display 98. The controller 12 includes control logic to detect when the DPF 86 requires regeneration. This information may be communicated to the operator using cluster display 98. Depending on the particular application and implementation, cluster display 98 may also provide a user input to request a manual or operator-initiated DPF regeneration using a touch screen, switch, button, etc. The controller 12 may also communicate with a proximity sensor 110, described in more detail below. Proximity sensor 110 may be used to detect an object within a predetermined distance of the exhaust with cluster display 98 used to display a corresponding message when DPF regeneration is otherwise indicated.

Referring now to FIG. 2, a vehicle 100 including the engine 10 and exhaust after-treatment system 80 is shown. The vehicle 100 includes the proximity sensor 110 mounted along the rear panel or portion 112 of the vehicle. In one embodiment, as illustrated in FIG. 2, the proximity sensor 110 is mounted on the bumper 114 of the vehicle 100. In another embodiment, the vehicle 100 may include a plurality of proximity sensors 110 which are mounted at spaced apart locations along the rear portion 112. By mounting the proximity sensors 110 along the rear portion 112 or the bumper 114, the proximity sensors 110 may be mounted adjacent an exhaust opening or tailpipe 116.

In most vehicles, DPF regeneration can occur while the vehicle is driving during normal operation because the exhaust temperature and regeneration strategies may be implemented with little or no effect on the drivability of the vehicle. However, some vehicles and drivers never experience drive cycles which allow automatic regeneration. For example, urban commuters and utility trucks, which do not experience highway driving and/or have start-and-stop driving cycles, will generally not have exhaust temperatures sufficient for regeneration and, therefore, need to have operator initiated regeneration. Elevated exhaust temperatures may adversely affect objects in the proximity of the engine exhaust opening during an operator-initiated regeneration when the vehicle is stopped. The exhaust temperature may be between 400° C. and 600° C. which may adversely impact people or objects such as trees, buildings, garage doors, fuel containers, or other combustible objects close to the exhaust during regeneration.

The proximity sensors 110 may be used to detect the presence and/or distance of an object 120 from the tailpipe 116 to control the regeneration of the DPF 86. The proximity sensors 110 are sensors which may detect a distance of an object from the sensor. Proximity sensors 110 may be any suitable sensors such as a sonar-based proximity sensor, a laser-based proximity sensor, an ultrasonic-based proximity sensor, or any other sensor suitable for detecting the presence and/or distance of an object. The proximity sensors 110 may include electrical wiring for electrically connecting the proximity sensor 110 to the controller 12 or, alternatively, the proximity sensors 110 may communicate wirelessly with the controller 12. The proximity sensors 110 may be parking-aid sensors or back-up sensors already present in some vehicle systems. By utilizing existing components, this DPF regeneration system minimizes cost and vehicle complexity. The proximity sensors 110 may also offer advantages over back-up cameras which require operator monitoring and do not automatically detect the distance of an object 120. Further, it is possible to include a plurality of proximity sensors 110 located at spaced apart locations to offer a wider range for detecting objects 120 behind and along the side of the vehicle 100, for example.

In one embodiment, vehicle 100 includes a proximity sensor 110 disposed adjacent to an exhaust opening of tailpipe 116 and positioned to detect distance “x” and/or presence of an object 120 near the opening. Controller 12, in communication with proximity sensor 110 is adapted for controlling regeneration of particulate filter 86 in response to proximity sensor 110 detecting object 120 near the opening. In the representative embodiment illustrated in FIG. 2, a plurality of proximity sensors 110 are mounted on bumper 114 of vehicle 100 proximate the exhaust opening of tailpipe(s) 116.

Referring now to FIG. 3, a simplified block diagram or flowchart is shown illustrating operation of a system for controlling the regeneration of the DPF using proximity sensors 110. The regeneration event may be operator-initiated or automatically initiated in appropriate vehicle circumstances. As those of ordinary skill in the art will understand, the functions represented by the flowchart may be performed by hardware and/or software. Depending on the particular processing strategy, such as event driven, interrupt driven, etc., the various functions may be performed in an order or sequence other than that illustrated in FIG. 3. Likewise, one or more steps or functions may be repeatedly performed although not explicitly illustrated. Similarly, one or more of the steps or functions illustrated may be omitted in some applications or implementations. In one embodiment, the functions illustrated are primarily implemented by software instructions, code, or control logic stored in a computer-readable storage medium and executed by a microprocessor based computer or controller to control operation of the vehicle, such as controller 12 (FIG. 1).

First, the controller monitors the DPF conditions, as represented by a block 210. Various strategies may be used to determine the condition of the DPF and whether the DPF should be regenerated. In some examples, a threshold pressure differential across the DPF may be used to determine the condition of the DPF and whether the DPF should be regenerated. However, in other examples, condition of the DPF is approximated based on vehicle mileage or hours of engine operation and whether the vehicle has traveled over a threshold distance or has surpassed a threshold time interval of engine operation. In another example, as illustrated in FIG. 3, the condition of the DPF and whether the DPF should be regenerated is determined based on whether the amount of stored particulate is greater than a maximum threshold.

As represented by block 212, the vehicle cluster display or message center may display information for the operator based on the condition of the DPF. Of course, a dedicated light or other service indicator may be used to convey similar information to the operator. The amount of particulate accumulated in the DPF may be displayed as a percentage where 100% would indicate that the DPF is full and requires regeneration. Alternatively, a percentage representing estimated remaining DPF capacity could be used. As the DPF nears a corresponding threshold, such as 100% particulate load, the vehicle cluster display informs the operator that the exhaust filter is full, as represented by block 214. The vehicle cluster display may also display a message requesting operator input. The operator input may include pressing a button or switch or pressing an input on the vehicle cluster display or some other input from the operator such as a sequence of putting the vehicle in park and/or depressing the brake pedal, accelerator pedal, etc.

Once the controller has received the operator input, the controller checks the vehicle surroundings using the proximity sensors, as represented by block 216. The controller determines if any objects are within a threshold distance of the vehicle. If any objects are detected within the threshold distance of the vehicle, the vehicle cluster display displays an appropriate message to the operator indicating that regeneration has been inhibited as represented by block 220. In one embodiment, the threshold distance may be a fixed distance within which distance regeneration is inhibited. In another embodiment, the threshold distance may be a variable distance depending on various circumstances, such as the type of object detected by the proximity sensors. For example, if the proximity sensors detect a metallic object, the threshold distance may be less than if the proximity sensors detect an object such as a person or a tree. The threshold distance may also be variable depending on the detected exhaust temperature. If the exhaust temperature is lower, the threshold distance may be shorter. Alternatively, the sensors may only detect the presence of an object and indicate a yes/no signal if the object is within the range of the sensors, where the range of the sensors may be the threshold distance. Depending on the application, the threshold distance may be one meters to five meters, for example. Of course, other threshold distances are contemplated depending on the exhaust conditions.

If the controller does not detect any objects within a threshold distance of the vehicle, the vehicle cluster displays a message to the operator requesting the operator to confirm the vehicle is in a suitable location to initiate regeneration, as represented by block 222. The operator may indicate the vehicle is in a suitable location using the operator input, as previously described. When the controller receives confirmation input, the controller initiates DPF regeneration as represented by block 223 using a strategy as previously described to increase the temperature of the exhaust provided to the DPF. The vehicle cluster display may then display a message to the operator indicating a regeneration event is occurring, as represented by block 224.

Once the DPF regeneration is initiated, the controller may continue to monitor the surroundings of the vehicle using the proximity sensors during the regeneration event as represented by block 226. If the controller does not sense any objects within the threshold distance, the regeneration event continues to complete cleaning of the exhaust filter, as represented by block 228. However, if the proximity sensors detect an object within the threshold distance during DPF regeneration, the controller suspends and/or terminates the regeneration event, as represented by block 229. The vehicle cluster display then displays an associated message that the exhaust cleaning has stopped as represented by block 230. The vehicle cluster display may also indicate that an object has been detected near the exhaust as represented by block 232.

Regeneration of the DPF may also be terminated by the operator, or stopped because of various vehicle conditions. The operator may terminate the regeneration event through an input such as pressing the brake pedal, shifting the vehicle into a drive gear, or by pressing a button or switch, for example. Once the regeneration event is terminated, the vehicle cluster display will indicate that the exhaust cleaning has stopped, as represented by block 230, and the operator may reset the process.

In parallel with monitoring the proximity sensors, the controller monitors the regeneration event to determine if the exhaust cleaning is completed, as represented by block 234. Monitoring of the regeneration event may include monitoring differential pressure or continuing the event for a specified time period, for example. The controller will automatically terminate the regeneration event when the DPF is cleaned and the vehicle cluster display will display a message indicating to the operator that the exhaust filter is cleaned and regeneration is completed, as represented by block 236.

Those of ordinary skill in the art will recognize that various features of the present disclosure may be applied to engine and vehicle applications other than DPF regeneration where exhaust temperatures within some proximity of the vehicle may adversely affect surrounding objects.

As such, systems and methods for controlling DPF regeneration according to the present disclosure reduce or eliminate the possibility for heat discharged during regeneration to adversely affect any object or person near the vehicle exhaust. Use of existing vehicle proximity sensors that may also be used for parking and/or back-up maneuvers provides additional feature functionality without requiring additional vehicle hardware and associated costs and complexity.

While the best mode has been described in detail, those familiar with the art will recognize various alternative designs and embodiments within the scope of the following claims. Various embodiments may have been described as providing advantages or being preferred over other embodiments and/or prior art devices in regard to one or more desired characteristics. However, as one skilled in the art is aware, one or more characteristics may be compromised to achieve desired overall system attributes, which depend on the specific application. These attributes include, but are not limited to: cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc. Any embodiments described herein as being less desirable in one aspect or another to other embodiments and/or prior art devices with respect to one or more characteristics are not outside the scope of the disclosure or claims. 

1. A method of controlling regeneration of a particulate filter in a vehicle engine exhaust, comprising: detecting a distance of an object from the exhaust; and controlling a regeneration event if the distance is less than a threshold value.
 2. The method of claim 1 wherein controlling comprises terminating the regeneration event.
 3. The method of claim 1 wherein controlling comprises preventing initiation of the regeneration event.
 4. The method of claim 1 further comprising displaying a message for an operator if the distance is less than the threshold value.
 5. The method of claim 1 further comprising displaying information about the particulate filter for an operator.
 6. The method of claim 5 further comprising initiating the regeneration event in response to input by the operator.
 7. The method of claim 1 further comprising detecting the distance using at least one proximity sensor mounted proximate the exhaust.
 8. The method of claim 1 further comprising detecting the distance using a proximity sensor mounted on a bumper of the vehicle.
 9. The method of claim 1 further comprising detecting the distance using a plurality of proximity sensors mounted proximate the exhaust.
 10. A method of controlling regeneration of a diesel particulate filter in a vehicle engine exhaust, comprising: providing a plurality of proximity sensors with at least one proximity sensor mounted proximate an exhaust exit; detecting a distance of an object from the exhaust; allowing regeneration of the particulate filter if the distance is greater than a threshold value; and terminating the regeneration of the particulate filter if the distance becomes less than the threshold value.
 11. The method of claim 10 further comprising displaying a message for an operator if the distance is less than the threshold value.
 12. The method of claim 10 further comprising providing the plurality of proximity sensors mounted at spaced apart locations along a vehicle bumper.
 13. A system comprising: a particulate filter disposed in an exhaust of a vehicle; a proximity sensor disposed adjacent an exhaust opening and positioned to detect presence of an object near the opening; and a controller in communication with the proximity sensor adapted for controlling regeneration of the particulate filter in response to the proximity sensor detecting the object near the opening.
 14. The system of claim 13 wherein the proximity sensor is mounted on a bumper of the vehicle.
 15. The system of claim 13 further comprising a plurality of proximity sensors mounted proximate the exhaust opening.
 16. The system of claim 13 further comprising a display in communication with the controller for displaying information to an operator about regeneration of the particulate filter.
 17. The system of claim 16 wherein the display displays a message to indicate presence of the object when regeneration is otherwise indicated.
 18. The system of claim 13 further comprising an operator input in communication with the controller for controlling regeneration of the particulate filter.
 19. The system of claim 13 further comprising: a display in communication with the controller for displaying information to an operator about regeneration of the particulate filter; and an operator input in communication with the controller, wherein a signal from the operator input initiates and terminates regeneration.
 20. The system of claim 13 further comprising: a display in communication with the controller for displaying information about the particulate filter to an operator; and an input in communication with the controller, wherein a signal from the input initiates regeneration, wherein the controller automatically terminates regeneration if the distance detected by the proximity sensor is less than the threshold value. 